1 /* 2 * Copyright (c) 2012, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 */ 23 24 import javax.swing.*; 25 import java.awt.*; 26 import java.awt.dnd.Autoscroll; 27 28 public class JListWithScroll<E> extends JList<E> implements Autoscroll { 29 private Insets scrollInsets; 30 JListWithScroll(E[] listData)31 public JListWithScroll(E[] listData) { 32 super(listData); 33 scrollInsets = new Insets(50, 50, 50, 50); 34 } 35 36 @Override getAutoscrollInsets()37 public Insets getAutoscrollInsets() { 38 return scrollInsets; 39 } 40 41 @Override autoscroll(Point cursorLoc)42 public void autoscroll(Point cursorLoc) { 43 JViewport viewport = getViewport(); 44 45 if (viewport == null) { 46 return; 47 } 48 49 Point viewPos = viewport.getViewPosition(); 50 int viewHeight = viewport.getExtentSize().height; 51 int viewWidth = viewport.getExtentSize().width; 52 53 if ((cursorLoc.y - viewPos.y) < scrollInsets.top) { 54 viewport.setViewPosition(new Point(viewPos.x, Math.max(viewPos.y - scrollInsets.top, 0))); 55 } else if (((viewPos.y + viewHeight) - cursorLoc.y) < scrollInsets.bottom) { 56 viewport.setViewPosition( 57 new Point(viewPos.x, Math.min(viewPos.y + scrollInsets.bottom, this.getHeight() - viewHeight)) 58 ); 59 } else if ((cursorLoc.x - viewPos.x) < scrollInsets.left) { 60 viewport.setViewPosition(new Point(Math.max(viewPos.x - scrollInsets.left, 0), viewPos.y)); 61 } else if (((viewPos.x + viewWidth) - cursorLoc.x) < scrollInsets.right) { 62 viewport.setViewPosition( 63 new Point(Math.min(viewPos.x + scrollInsets.right, this.getWidth() - viewWidth), viewPos.y) 64 ); 65 } 66 67 } 68 getViewport()69 public JViewport getViewport() { 70 Component curComp = this; 71 72 while (!(curComp instanceof JViewport) && (curComp != null)) { 73 curComp = curComp.getParent(); 74 } 75 if(curComp instanceof JViewport) { 76 return (JViewport) curComp; 77 } else { 78 return null; 79 } 80 } 81 } 82